linux-kernel - [PATCH 1/4] interconnect: qcom: icc-rpm: Add AB/IB calculations coefficients

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Message-Id: <20230726-topic-icc_coeff-v1-1-31616960818c@linaro.org>
Date:   Wed, 26 Jul 2023 18:25:43 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Georgi Djakov <djakov@...nel.org>
Cc:     Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Konrad Dybcio <konrad.dybcio@...aro.org>
Subject: [PATCH 1/4] interconnect: qcom: icc-rpm: Add AB/IB calculations
 coefficients

Presumably due to the hardware being so complex, some nodes (or busses)
have different (usually higher) requirements for bandwidth than what
the usual calculations would suggest.

Looking at the available downstream files, it seems like AB values are
adjusted per-bus and IB values are adjusted per-node.
With that in mind, introduce percentage-based coefficient struct members
and use them in the calculations.

One thing to note is that downstream does (X%)*AB and IB/(Y%) which
feels a bit backwards, especially given that the divisors for IB turn
out to always be 25, 50, 200 making this a convenient conversion to 4x,
2x, 0.5x.. This commit uses the more sane, non-inverse approach.

Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
---
 drivers/interconnect/qcom/icc-rpm.c | 10 +++++++++-
 drivers/interconnect/qcom/icc-rpm.h |  5 +++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/interconnect/qcom/icc-rpm.c b/drivers/interconnect/qcom/icc-rpm.c
index 2c16917ba1fd..2de0e1dfe225 100644
--- a/drivers/interconnect/qcom/icc-rpm.c
+++ b/drivers/interconnect/qcom/icc-rpm.c
@@ -298,9 +298,11 @@ static int qcom_icc_bw_aggregate(struct icc_node *node, u32 tag, u32 avg_bw,
  */
 static void qcom_icc_bus_aggregate(struct icc_provider *provider, u64 *agg_clk_rate)
 {
-	u64 agg_avg_rate, agg_rate;
+	struct qcom_icc_provider *qp = to_qcom_provider(provider);
+	u64 agg_avg_rate, agg_peak_rate, agg_rate;
 	struct qcom_icc_node *qn;
 	struct icc_node *node;
+	u16 percent;
 	int i;
 
 	/*
@@ -315,6 +317,12 @@ static void qcom_icc_bus_aggregate(struct icc_provider *provider, u64 *agg_clk_r
 			else
 				agg_avg_rate = qn->sum_avg[i];
 
+			percent = qp->ab_percent ? qp->ab_percent : 100;
+			agg_avg_rate = mult_frac(percent, agg_avg_rate, 100);
+
+			percent = qn->ib_percent ? qn->ib_percent : 100;
+			agg_peak_rate = mult_frac(percent, qn->max_peak[i], 100);
+
 			agg_rate = max_t(u64, agg_avg_rate, qn->max_peak[i]);
 			do_div(agg_rate, qn->buswidth);
 
diff --git a/drivers/interconnect/qcom/icc-rpm.h b/drivers/interconnect/qcom/icc-rpm.h
index eed3451af3e6..dbb3146a81c4 100644
--- a/drivers/interconnect/qcom/icc-rpm.h
+++ b/drivers/interconnect/qcom/icc-rpm.h
@@ -45,6 +45,7 @@ struct rpm_clk_resource {
  * @regmap: regmap for QoS registers read/write access
  * @qos_offset: offset to QoS registers
  * @bus_clk_rate: bus clock rate in Hz
+ * @ab_percent: a percentage-based coefficient for compensating the AB calculations
  * @bus_clk_desc: a pointer to a rpm_clk_resource description of bus clocks
  * @bus_clk: a pointer to a HLOS-owned bus clock
  * @intf_clks: a clk_bulk_data array of interface clocks
@@ -58,6 +59,7 @@ struct qcom_icc_provider {
 	struct regmap *regmap;
 	unsigned int qos_offset;
 	u32 bus_clk_rate[QCOM_SMD_RPM_STATE_NUM];
+	u16 ab_percent;
 	const struct rpm_clk_resource *bus_clk_desc;
 	struct clk *bus_clk;
 	struct clk_bulk_data *intf_clks;
@@ -93,6 +95,7 @@ struct qcom_icc_qos {
  * @num_links: the total number of @links
  * @channels: number of channels at this node (e.g. DDR channels)
  * @buswidth: width of the interconnect between a node and the bus (bytes)
+ * @ib_percent: a percentage-based coefficient for compensating the IB calculations
  * @sum_avg: current sum aggregate value of all avg bw requests
  * @max_peak: current max aggregate value of all peak bw requests
  * @mas_rpm_id:	RPM id for devices that are bus masters
@@ -106,6 +109,7 @@ struct qcom_icc_node {
 	u16 num_links;
 	u16 channels;
 	u16 buswidth;
+	u16 ib_percent;
 	u64 sum_avg[QCOM_SMD_RPM_STATE_NUM];
 	u64 max_peak[QCOM_SMD_RPM_STATE_NUM];
 	int mas_rpm_id;
@@ -123,6 +127,7 @@ struct qcom_icc_desc {
 	enum qcom_icc_type type;
 	const struct regmap_config *regmap_cfg;
 	unsigned int qos_offset;
+	u16 ab_percent;
 };
 
 /* Valid for all bus types */

-- 
2.41.0